1. Field of the Invention
The present invention relates to railroad draft gear and more particularly to a lockout control apparatus for locking a shock absorbing draft gear against relative damping movement when a railroad train is travelling in over-the-road conditions in order to reduce train action.
2. Description of the Prior Art
Shock absorbing draft gears are well known wherein each railroad car is provided at each end thereof with a coupler operatively connected to shock absorbing means arranged in a housing whereby the coupler is cushioned when subjected to shock. The shock absorbing means can be hydraulic or mechanical.
However, even though the longitudinal movement of such couplers is limited to within a few inches, it is obvious that in a train, especially comprising 100 cars or more, the accumulative effect of either the cars buffing together or drafting during over-the-road travel causes undesirable oscillations known as train action and can result in derailment.
Lock-out type draft gear have been suggested such as in U.S. Pat. No. 3,236,395, Peterson 1966. In that Patent, a draft gear of the dual sliding sill type is provided with pivoting locking plates in order to mechanically lock the draft gear against buffing in response to a decrease in pressure in the train brake line.
U.S. Pat. No. 3,414,134, Nealis 1968 shows a hydraulic lock-out device where the draw bar is in the form of a piston in the housing which acts as the cylinder. A fluid passageway is provided to allow circulation between the chambers formed on both sides of the piston head and a gate valve is operable to block the passageway thus locking out the draw gear.
The gate valve is controlled by separate control means associated with the throttle and the braking system of the train. It would appear that all of the cars of a single train would need to be so modified before the lock-out system can be used.